1. Field of the Invention
The invention relates to a rocker-sliding bearing for bridges or similar structures including a flat top plate, an intermediate plate having a flat top side and a concave curved underside, and a baseplate having a correspondingly concave curved top side in turn secured to a bedplate, the curved surface on the top of the baseplate being provided with a lining of efficiently corrosion-resistant material and the curved surface of the intermediate plate being lined with a material which has a low coefficient of friction relative to the highly corrosion-resistant material on the curved surface of the baseplate. The invention also relates to a method of lining the concave top side of the baseplate of the aforementioned rocker-sliding bearing.
2. Description of the Prior Art
Rocker-sliding bearings for bridges or other structures, which have to bear heavy loads, usually have spherical sliding surfaces in the form of a frictional combination of PTFE and hard chromium. The PTFE layer is usually applied to cavities in the concave top side of the base of the bearing, whereas the curved underside of the intermediate plate or "cap", which abuts the PTFE layer and is convex to match the concave underlayer, has its surface lined with hard chromium. It has previously been attempted to insert the PTFE layer in the convex surface of the cap, whereas the concave top side of the base of the bearing is provided with a hard chromium layer.
It has been found, however, that it is relatively expensive to coat the aforementioned spherical, particularly concave, surfaces with hard chromium, and it is difficult to give the layer the required uniformity. A fairly large amount of manual labor is also required for the preliminary polishing before chromium-plating and, more particularly, is also necessary after the plating. It is also necessary to apply an anti-corrosive layer having good frictional properties.
Previously published licences of bridge bearings by the Institut fur Bautechnik, Berlin, relate exclusively to the use of PTFE on one frictional side, whereas a layer of hard chromium is applied to the other frictional side. This means that bearings hitherto licensed by the building authorities have been plated with hard chromium, with all the attendant difficulties.